High water levels at Lake Red Rock near Pella, Iowa, have subsided and on June 13, Missouri River Energy Services (MRES) authorized upstream work to resume on the Red Rock Hydroelectric Project (RRHP). MRES is building the project on the existing Red Rock Dam located on the Des Moines River.

Construction of the intake structure on the upstream side of the Red Rock Dam was halted on May 25 as crews prepared for water levels to rise above the 750-foot elevation of the work platform. Equipment was removed from the site and crews pre-flooded the area in a controlled manner to minimize damage from the eminent flooding of the work platform.

Lake Red Rock water levels reached the 750-foot elevation of the work platform on May 27 and remained at that level or higher through June 5. Crews began a dewatering process on June 13 and the worksite dried out sufficiently to allow work to resume the week of June 19.

When completed, the intake structure will collect water from the Red Rock reservoir, remove any floating trash, and direct the water through penstocks or channels to two turbine generators located in the powerhouse on the downstream side of the dam. The flowing water drives the turbines that power the generators. The water is then slowed down and returned to the Des Moines River through a tailrace channel.

There is little work left to be done upstream before crews will start to build the intake structure itself. All of the excavation bracing has been installed. Removal of the final 10 feet of dirt around the drilled shafts (intake structure foundation supports) is now underway.

Next, a “mud mat” or rough concrete slab with no rebar, will be poured to create a clean surface for the first structural pour of concrete for the intake. It is anticipated that the first structural pour will take place in late July. During this same time, crews will continue to excavate to prepare for construction of the two penstocks, which will carry the water from the upstream intake to the downstream powerhouse.